The Internet can bring with it a great deal of undesirable traffic, including hackers, spam bots, spyware and more. Hackers can access private information, steal user identities, create zombie computers for forwarding spam e-mail and other harmful activities. Firewalls provide a great deal of protection against unwanted access, but network administrators will gain a valuable tool by learning to control traffic to their networks. Administrators can accomplish by modifying network router settings to block a range of IP addresses or entire websites.
Enter your default gateway IP address into a Web browser. This can be found by typing "ipconfig" in the command prompt in Windows. For Macs, see the next step. This IP address will connect you directly to your router administration interface.
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Select "System Preferences" from the Apple menu (for Mac users). Then choose "Network" under the "View" menu. Next, set the correct port setting (e.g., if you're using a wireless connection, choose "AirPort"; if you're on a broadband connection, choose "Ethernet"). Finally, select "Advanced...." Your default gateway address will appear next to "Router:" under the "TCP/IP" tab.
Log into your Wireless or LAN router (if you are connected to it by an Ethernet cable). If you don't know your password, contact your network administrator or reset your modem and look on the outside of the modem itself for default login settings. If they are not visible, contact the modem manufacturer.
Locate the list of enabled/disabled IP addresses. Most wireless routers will enable you to identify one or a range of IP addresses to block from accessing your network. You can find this in Linksys, for example, under the "Access Restrictions" tab.
Enter the IP addresses you wish to block. Then select "deny" from the configuration settings. Optionally, you can enter the IP addresses you wish to permit to access your network and select "allow" from the configuration settings. This will deny access to anyone not on your approved list.
Enter the name of a website you wish to block. Most routers also support filtering by website URL, though this will only prevent any users accessing your network through that website and may not be specific enough to catch individual unwanted IP addresses.